Add correct breadcrumb levels for 4xx/5xx response codes

[sl0thentr0py]

see getsentry/team-sdks#100

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 69.70%. Comparing base (cfd5059) to head (0711de3).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
sentry-ruby/lib/sentry/utils/http_tracing.rb	25.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2549      +/-   ##
==========================================
+ Coverage   67.90%   69.70%   +1.80%     
==========================================
  Files         118      126       +8     
  Lines        4483     4737     +254     
==========================================
+ Hits         3044     3302     +258     
+ Misses       1439     1435       -4     

Components	Coverage Δ
sentry-ruby	60.63% <25.00%> (+0.51%)	⬆️
sentry-rails	97.48% <ø> (ø)
sentry-sidekiq	95.52% <ø> (∅)
sentry-resque	92.64% <ø> (ø)
sentry-delayed_job	95.65% <ø> (ø)
sentry-opentelemetry	100.00% <ø> (ø)

Files with missing lines	Coverage Δ
sentry-ruby/lib/sentry/utils/http_tracing.rb	28.20% <25.00%> (-0.83%)	⬇️

... and 12 files with indirect coverage changes

[solnic]

Left some minor suggestions, otherwise LGTM